440A stainless steel has excellent quenching and hardening performance, high hardness, and higher toughness than 440B steel and 440C steel. Used as cutting tool, measuring tool and bearing.
The carbon content and hardness of 440A, 440B, 440C increased from A-B-C successively (A-0.75%, B-0.9%, C-1.2%). The 440C is an excellent high-end stainless steel, usually up to 56-58RC. The rust resistance of these three steels is good, 440A is the best, while 440C is the lowest. 440C is very common.
The chemical composition of martensite stainless steel is characterized by adding elements such as molybdenum, tungsten, vanadium and niobium on the basis of different composition combinations of 0.1%-1.0% C and 12%-27% Cr. Because the organization structure is body - centered cubic structure, the strength decreases sharply at high temperature. And below 600℃, high temperature strength in all kinds of stainless steel, creep strength is the highest.
440A has excellent quenching and hardening performance, high hardness, and higher toughness than 440B steel and 440C steel.
440B Used for cutting tools, measuring tools, bearings and valves, 440B has higher hardness than 440B steel, higher toughness than 440C steel.
The 440C has the highest hardness of all stainless steel and heat resistant steels, used for nozzles and bearings.The 440F is used in automatic lathes to improve the cutting performance of 440C steel.